Recording materials

ABSTRACT

Vesicular recording materials are described which include a sensitized layer comprising a polyeric vehicle for the sensitizing agent which is an acrylonitrile/substituted or unsubstituted styrene copolymer with at least 55 mole % of acrylonitrile and preferably less than 85 mole %. The copolymer is usually homogeneous and preferably derived from acrylonitrile and the styrene comonomer along and most preferably contains from 65 to 82 mole % of acrylonitrile. The copolymer is softenable on heating to permit the gas released by the sensitizing agent in the light struck areas to form light-scattering or reflecting vesicles therein. 
     A surfactant in an amount of at least 1% by weight, based on the weight of the copolymer, is essential to vesiculation and anionic surfactants are especially effective in providing a wide tonal range and good speed rating, amounts up to 20% by weight being preferred. Generally, amounts of the surfactant in the range 2 to 5% by weight provide a satisfactory combination of vasiculating properties. The sensitized layer is preferably applied as a coating to a carrier sheet support such as a polythylene terephthalate film. These recording materials have excellent vesiculating properties, particularly tonal range and speed rating.



